Many transition metal complexes have heretofore been used as catalysts for preparation of organic compounds. In particular, noble metal complexes are stable and are easy to handle although those are expensive. Thus, extensive investigations are made on syntheses utilizing such noble metal complexes as catalysts. In particular, many reports are issued with respect to asymmetric catalysts used in asymmetric syntheses such as asymmetric isomerization reaction and asymmetric hydrogenation reaction.
In general, rhodium, palladium and nickel catalysts with tert-phosphine as an optically active ligand provided thereto give good results. Japanese Patent Application (OPI) No. 61937/80, for example, discloses a rhodium/phosphine catalyst as an asymmetric hydrogenation catalyst, in which chiral phosphine is coordinated to rhodium. The term "OPI" as used herein means a "published unexamined Japanese patent application".
Japanese Patent Application (OPI) No. 4748/83 discloses an asymmetric hydrogenation catalyst and also discloses a method of preparing enamines or imines by isomerization of allylamine derivatives using as an asymmetric isomerization catalyst a rhodium complex represented by the formula (II): EQU [Rh(olefin)L].sup.+ X.sup.- (II)
wherein the olefin represents ethylene, 1,3-butadiene, norbornadiene or cycloocta-1,5-diene; X represents ClO.sub.4, BF.sub.4 or PF.sub.6 ; and L represents two triarylphosphines or a trivalent phosphine compound represented by the formula (III): ##STR1## wherein Z is ##STR2## For example, neryldiethylamine is subjected to isomerization and the enamine thus prepared is hydrolyzed to obtain optically active citronellal.
These catalysts, however, have various disadvantages. One of the disadvantages is that their production costs are high since they are prepared using expensive metals and their preparation steps are complicated. This results in increasing the price of the desired compound. Another disadvantage is that although their catalytic activity is high, such a high activity cannot be maintained for long periods of time, or conversely, although their catalytic life or durability is long, activity is relatively low. Thus, they are not suitable for use in industrial applications.
As a catalyst which can overcome the above-described disadvantages, Japanese Patent Application (OPI) No. 169283/83 (corresponding U.S. patent application Ser. No. 651,123, filed Sept. 17, 1984) discloses a rhodium-phosphine complex represented by the formula (IV) EQU [Rh(BINAP).sub.2 ].sup.+ Q.sup.- (IV)
wherein BINAP represents 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, and Q represents ClO.sub.4, PF.sub.6, BF.sub.4, PCl.sub.6 or B(C.sub.6 H.sub.5).sub.4. However, this catalyst is not completely satisfactory in industrial uses.
Under such circumstances, it has been desired to develop catalysts which are inexpensive, have a high activity and can maintain such a high activity for long periods of time.